ones complement

1 definition found

ones complement - Free On-line Dictionary of Computing (26 May 2007) :

  ones complement
  
     A system used in some computers to represent negative
     numbers. To negate a number, each bit of the number is
     inverted (zeros are replaced with ones and vice versa).  This
     has the consequence that there are two reperesentations for
     zero, either all zeros or all ones.
  
     	...
     	000...00011 = +3
     	000...00010 = +2
     	000...00001 = +1
     	000...00000 = +0
     	111...11111 = -0
     	111...11110 = -1
     	111...11101 = -2
     	111...11100 = -3
     	...
  
     Naive logic for ones complement addition might easily conclude
     that -0 + 1 = +0.
  
     The twos complement avoids this by using all ones to
     represent -1.